显示图标规范输入字符计数

在一键优化与撤销操作行右侧实时显示 Unicode 字符数和 200 字符上限。

补充计数更新、emoji 截断和右对齐布局测试，并同步编辑器方案文档。

src/components/image-editor/ImageCanvasSpecGenerationPanelView.test.tsx

@@ -355,6 +355,15 @@ describe('ImageCanvasSpecGenerationPanelView', () => {
       '玩法设定',
     ) as HTMLTextAreaElement;
     const artStyle = screen.getByLabelText('美术风格') as HTMLTextAreaElement;
+    expect(screen.getByLabelText('玩法设定字符计数').textContent).toBe(
+      '5/200',
+    );
+    expect(screen.getByLabelText('美术风格字符计数').textContent).toBe(
+      '4/200',
+    );
+    expect(screen.getByLabelText('玩法设定字符计数').className).toContain(
+      'ml-auto',
+    );
     expect(playSetting.hasAttribute('maxlength')).toBe(false);
     expect(artStyle.hasAttribute('maxlength')).toBe(false);
 
@@ -362,6 +371,9 @@ describe('ImageCanvasSpecGenerationPanelView', () => {
     expect(Array.from(playSetting.value)).toHaveLength(200);
     fireEvent.change(playSetting, { target: { value: '🎮'.repeat(201) } });
     expect(Array.from(playSetting.value)).toHaveLength(200);
+    expect(screen.getByLabelText('玩法设定字符计数').textContent).toBe(
+      '200/200',
+    );
     fireEvent.click(screen.getByRole('button', { name: '提交生成规范' }));
     expect(onSubmit).toHaveBeenCalledTimes(1);
 

src/components/image-editor/ImageCanvasSpecGenerationPanelView.tsx

@@ -554,6 +554,13 @@ export function ImageCanvasSpecGenerationPanelView({
                           撤销
                         </PlatformActionButton>
                       ) : null}
+                      <span
+                        className="ml-auto text-[10px] leading-4 tabular-nums text-slate-400"
+                        aria-label={`${item.title}字符计数`}
+                      >
+                        {getIconSpecPromptLength(value)}/
+                        {EDITOR_ICON_SPEC_PROMPT_MAX_LENGTH}
+                      </span>
                     </div>
                   </label>
                 );